Display device, keypad thereof and method for activating display device

ABSTRACT

A display device includes a processor, a memory, an interface and a keypad. The keypad, separably connected to the interface, includes a signal generator. When the display device is connected to a power source, the processor sends a first signal to the interface. The signal generator generates a second signal in response to the first signal. The processor determines whether the second signal is correct based on data stored in the memory. If yes, the display device may be activated. A method for activating the display device via the separable keypad comprises the steps of: connecting the display device to the power source; the display device sending the first signal to the interface; determining whether the second signal is correct; and if yes, activating the display device.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority to Taiwan Patent Application No.094135379 filed on Oct. 11, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device, keypad thereof andmethod for activating a display device; more specifically, relates to adisplay device and a method for activating the display device by using aseparable keypad.

2. Descriptions of the Related Art

The types of the display devices on the market are very various. Aprojector, for example, has high risk of being stolen because it isquite valuable and easily exposed to the public. In order to prevent theprojector from being stolen, projector manufacturers install king locksto lock the projector. However, because these king locks can be easilydestroyed, the burglarproof effect is unsatisfactory.

In conclusion, the existing technology for preventing the display devicefrom being stolen often faces problems, given that the burglarproofstructure can be easily destroyed. Therefore, there is still a need forfinding ways to protect display devices from being stolen.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a display devicecomprising a processor, a memory, an interface and a keypad. The memorystores a first data. The keypad, separably connected to the interface,comprises a signal generator. When the display device is connected to apower source, the processor sends a first signal to the interface. Thesignal generator generates a second signal in response to the firstsignal. The processor determines whether the second signal is correctaccording to the first data. If yes, the display device may beactivated.

Another object of the present invention is to provide the aforementionedkeypad. The keypad, separably connected to a display device, comprisesan interface and a signal generator, wherein the interface is configuredto connect to the display device and the signal generator is connectedto the interface. When the display device is connected to a powersource, the display device sends a first signal to the interface. Thesignal generator generates a second signal in response to the firstsignal. The second signal is sent to the display device by theinterface. The display device determines whether to be activatedaccording to the second signal. If the keypad is not connected to thedisplay device, the display device cannot be activated.

Another object of the present invention is to provide a method foractivating a display device by using a separable keypad. The displaydevice comprises an interface and a power button. The interface isconnected to a keypad separably. The display device stores a first data.The method comprises the following steps: connecting the display deviceto a power source; the display device sending a first signal to theinterface; determining whether a second signal received from the keypadvia the interface is correct according to the first data; and if yes,waiting for the power button being pressed to activate the displaydevice.

Accordingly, when users do not use a display device any more, the keypadof the present invention may be taken away. Even a burglar steals thedisplay device, the display device cannot be activated. Such idea detersa burglar from stealing the display device of the present invention andalso avoids that a lock, e.g., a king lock is easily destroyed.

The detailed technology and preferred embodiments implemented for thesubject invention are described in the following paragraphs accompanyingthe appended drawings for people skilled in this field to wellappreciate the features of the claimed invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a first embodiment of the presentinvention;

FIG. 2 is a block diagram of the first embodiment of the presentinvention;

FIG. 3 is a block diagram of an example of a keypad of the presentinvention;

FIG. 4 is a block diagram of another example of a keypad of the presentinvention; and

FIG. 5 is a flow chart of a second embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A first embodiment of the present invention is a projection displayapparatus 1 as illustrated in FIG. 1 and FIG. 2. The projection displayapparatus 1 comprises a mainframe 11 and a separable keypad 12. Themainframe 11 comprises a processor 101, a memory 103 and an interface105. When the projection display apparatus 1 is connected to a powersource, the processor 101 generates a first signal 100 that is a digitalsignal comprising a plurality of bits. The interface 105 is configuredto connect to the separable keypad 12. The keypad 12 comprises a signalgenerator 107 that generates a second signal 102 in response to thefirst signal 100. The memory 103 stores a first data. When the processor101 receives the second signal 102 via the interface 105, the processor101 determines whether the second signal 102 is correct according to thefirst data. If yes, the projection display apparatus 1 may be activatedand then operates normally.

One example of the keypad 12 is illustrated in FIG. 3. The keypad 12comprises an interface 301, a key scanning circuit 303 and a signalgenerator 107. The interface 301, connected to the interface 105 of themainframe 11, comprises eight signal terminals KEY1˜KEY8, a decodingcontrol terminal DATA, a clock terminal CLOCK, and a clear terminalCLEAR. The key scanning circuit 303 comprises a plurality of buttons.When the interface 301 is connected to the interface 105 and theprojection display apparatus 1 operates normally, the key scanningcircuit 303 generates a voltage once one button of the key scanningcircuit 303 is pressed. The voltage is sent to the interface 105 via acorresponding terminal of the eight signal terminals KEY1˜KEY8 in orderto control the projection display apparatus 1. The signal generator 107comprises a shift register 309 of type 74164 and inverters 305 and 307both of which are electrically connected to the buttons of the keyscanning circuit 303. The decoding control terminal DATA is configuredto input a decoding control signal 300. The clock terminal CLOCK isconfigured to input a clock signal 302.

More specifically, the above-mentioned first signal 100 is the decodingcontrol signal 300 illustrated in FIG. 3, which is inputted to thesignal generator 107 via the decoding control terminal DATA. Thedecoding control signal 300 successively sends a signal [1], a signal[0], a signal [1], a signal [1], a signal [1], a signal [1], a signal[0] and a signal [1] at the rising edges of the clock signal 302. Thesignal generator 107 shifts and outputs the bits to output terminals QH,QG; QF, QE, QD, QC, QB and QA after receiving them. As FIG. 3 shows, theoutput terminal QB is connected to the inverter 305 and the outputterminal QG is connected to the inverter 307. These bits form the secondsignal 102. For example, in response to the first signal 100, from theeight signal terminals KEY1˜KEY8 a logic signal [0 1 0 0 0 0 1 1] may beread at the first rising edge of the clock signal 302, a logic signal [01 0 0 0 0 0 0] may be read at the second rising edge of the clock signal302, a logic signal [0 1 0 0 0 1 1 1] may be read at the third risingedge of the clock signal 302, a logic signal [0 1 0 0 1 0 0 1] may beread at the fourth rising edge of the clock signal 302, a logic signal[0 1 0 1 0 1 0 1] may be read at the fifth rising edge of the clocksignal 302, a logic signal [0 1 1 0 1 1 0 1] may be read at the sixthrising edge of the clock signal 302, a logic signal [0 0 0 1 1 1 0 0]may be read at the seventh rising edge of the clock signal 302, and alogic signal [1 1 1 1 1 1 1 1] may be read at the eighth rising edge ofthe clock signal 302.

The projection display apparatus 1 determines whether the receivedsecond signal 102 is correct at every rising edge of the clock signal302 according to the first data stored in the memory 103. If all of thereceived second signals 102 in the successive eight clocks are correct,the projection display apparatus 1 may be activated normally. Otherwise,the projection display apparatus 1 cannot be activated.

Another example of the keypad 12 is illustrated in FIG. 4. The keypad 12comprises an interface 401, a key scanning circuit 403 and a signalgenerator 107. The interface 401, connected to the interface 105 of themainframe 11, comprises eight signal terminals KEY1˜KEY8 and decodingcontrol terminals WP, SCL, and SDA. The signal generator 107 is anelectrically erasable programmable read only memory (EEPROM) of type24C02 which stores a second data. When the interface 401 is connected tothe interface 105, the projection display apparatus 1 sends the firstsignal 100 to the keypad 12. In this example, the first signal 100includes a first decoding control signal 400, a second decoding controlsignal 402 and a third decoding control signal 404. When the firstdecoding control signal 400, the second decoding control signal 402, thethird decoding control signal 404 are inputted to the signal generator107 via the decoding control terminals WP, SCL, and SDA respectively,the signal generator 107 generates the second signal 102 in response tothe first decoding control signal 400, the second decoding controlsignal 402 and the third decoding control signal 404.

More specifically, the signal generator 107 outputs the second data viathe decoding control terminal SDA, which is a bi-directional I/Oterminal, to generate the second signal 102. The processor 101 comparesthe second signal 102 with the first data stored in the memory 103 afterreceiving the second signal 102. If the second signal 102 is identicalto the first data, the projection display apparatus 1 may be activatednormally. Otherwise, the projection display apparatus 1 cannot beactivated.

A second embodiment of the present invention is a method for activatinga display device. The display device is a projection display apparatuscomprising an interface and a power button, wherein the interface isseparably connected to a keypad. The projection display apparatus storesa first data. As shown in FIG. 5, the second embodiment comprises thefollowing steps. When step 501 is executed, the projection displayapparatus is connected to a power source. Then step 502 is executed, inwhich the projection display apparatus sends a first signal to theinterface. The keypad sends a second signal to the projection displayapparatus in response to the first signal. Then step 503 is executed, inwhich the projection display apparatus determines whether the secondsignal is correct according to the first data. If yes, that means theprojection display apparatus is allowed to be activated so step 504 isexecuted to wait for the power button being pressed to activate theprojection display apparatus. If not, the second embodiment goes back tostep 502, in which the projection display apparatus continuously sendsthe first signal to the interface.

The examples of the keypad in the first embodiment may be applied to thesecond embodiment. In other words, the keypad in the second embodimentmay be the examples illustrated in FIG. 3 or FIG. 4, i.e., the keypadcomprises a shift register or an EEPROM. If the keypad comprises theEEPROM, the projection display apparatus determines whether the firstdata is identical to the second data when step 503 is executed. If yes,step 504 is executed.

Based on the above description, the display device in accordance withthe present invention determines whether the display device may beactivated normally according to a signal from the keypad. For aburglarproof purpose, users may take the keypad away when the displaydevice is not used. The display device hence cannot be activatednormally. Such idea deters a burglar from stealing the display deviceand also avoids that a lock, e.g., a king lock is easily destroyed.

The above disclosure is related to the detailed technical contents andinventive features thereof. People skilled in this field may proceedwith a variety of modifications and replacements based on thedisclosures and suggestions of the invention as described withoutdeparting from the characteristics thereof. Nevertheless, although suchmodifications and replacements are not fully disclosed in the abovedescriptions, they have substantially been covered in the followingclaims as appended.

1. A display device, comprising: a processor; a memory for storing afirst data; an interface; and a keypad, separably connected to theinterface, comprising a signal generator; wherein when the displaydevice is connected to a power source, the processor sends a firstsignal to the interface, the signal generator generates a second signalin response to the first signal, the processor determines whether thesecond signal is correct based on the first data, and if yes, thedisplay device is activated.
 2. The display device as claimed in claim1, wherein the first signal is a digital signal comprising a pluralityof bits.
 3. The display device as claimed in claim 2, wherein the keypadfurther comprises a plurality of buttons, when the keypad is connectedto the interface, the keypad sends a voltage to the interface bypressing one of the buttons, the signal generator is electricallyconnected to the buttons and comprises a shift register, the shiftresister generates a plurality of voltages forming the second signal inresponse to the first signal.
 4. The display device as claimed in claim1, wherein the signal generator is an electrically erasable programmableread only memory (EEPROM), and when the keypad is connected to theinterface, the EEPROM generates the second signal in response to thefirst signal.
 5. The display device as claimed in claim 4, wherein theEEPROM stores a second data to generate the second signal.
 6. Thedisplay device as claimed in claim 5, wherein the processor determineswhether the second data is correct according to the first data.
 7. Thedisplay device as claimed in claim 1, wherein the display device is aprojection display apparatus.
 8. A keypad, separably connected to adisplay device, comprising: an interface for connecting to the displaydevice; a signal generator connected to the interface; wherein when thedisplay device is connected to a power source, the display device sendsa first signal to the interface, the signal generator generates a secondsignal in response to the first signal, the second signal is sent to thedisplay device by the interface, and the display device determineswhether to be activated according to the second signal.
 9. The keypad asclaimed in claim 8, further comprising a plurality of buttons, whereinthe keypad sends a voltage to the display device by pressing one of thebuttons when the keypad is connected to the display device, the signalgenerator is electrically connected to the buttons and comprises a shiftregister, and the shift register generates a plurality of voltagesforming the second signal in response to the first signal.
 10. Thekeypad as claimed in claim 8, wherein the signal generator is an EEPROM,and the EEPROM generates the second signal in response to the firstsignal when the keypad is connected to the display device.
 11. Thekeypad as claimed in claim 8, wherein the EEPROM stores a data forgenerating the second signal.
 12. The keypad as claimed in claim 8,wherein the display device is a projection display apparatus.
 13. Amethod for activating a display device, the display device comprising aninterface and a power button, the interface being separably connected toa keypad, the display device storing a first data, the method comprisingthe steps of: connecting the display device to a power source; thedisplay device sending a first signal to the interface; determiningwhether a second signal received from the keypad via the interface iscorrect according to the first data, if yes, going to step (d); andwaiting for the power button being pressed to activate the displaydevice.
 14. The method as claimed in claim 13, wherein if the secondsignal is determined incorrect in step (c), the method goes back to step(b).
 15. The method as claimed in claim 13, wherein the first signal isa digital signal comprising a plurality of bits.
 16. The method asclaimed in claim 15, wherein the keypad comprises: a plurality ofbuttons, when the keypad is connected to the interface, the keypadsending a voltage to the interface by pressing one of the buttons; and ashift register electrically connected to the buttons; wherein the methodfurther comprises: (e) the shift register generating a plurality ofvoltages forming the second signal in response to the digital signal.17. The method as claimed in claim 13, wherein the keypad comprises anEEPROM, and the method further comprises: (f) the EEPROM generating thesecond signal in response to the first signal when the interface isconnected to the keypad.
 18. The method as claimed in claim 17, whereinthe EEPROM stores a second data for generating the second signal. 19.The method as claimed in claim 18, wherein step (c) comprises: (g)determining whether the first data is identical to the second data, ifyes, going to step (d).
 20. The method as claimed in claim 13, whereinthe display device is a projection display apparatus.